To start an internal combustion engine or a combustion engine, a starter motor of the starter is conventionally used, the starter motor driving a starter pinion of the starter to mesh with a ring gear of the crankshaft when the internal combustion engine is at a standstill in order to crank the crankshaft via the pinion-ring gear mesh thus produced. Here, the starter cranks the combustion engine to a minimum rotational speed in such a way that the combustion process may take place automatically and a stable idle state of the combustion engine may be achieved. Compared to the use of conventional start systems without a start-stop functionality, the use of start-stop systems results in an increase in the start frequency.
The activation of the start-stop system conventionally takes place with the aid of a driver unit or a relay driver unit (RDU) which receives control signals from the control unit or the engine control unit and energizes the relay of the starter motor as a function of the received control signals. This energization, in turn, results in the starter pinion meshing with the motor ring gear. A conventional starter relay includes a pull-in winding and a hold-in winding. With the aid of the pull-in winding, a stronger current is provided to pull in the armature of the relay. With the aid of the hold-in winding, a weaker current is provided to hold the armature of the relay in a switched position.
Publication DE 102 22 162 A1 discusses a method and a device for activating starters in internal combustion engines. Here, a starter is described which includes a meshing solenoid. Furthermore, activation signals are generated for the starter and the meshing solenoid. After the transmission of a start intention to an input function block, its output signals are processed in a processing block. The latter includes a diagnostic function module, a safety function against an overload of the starter, and a sequence control. Activation signals, which are decoupled from one another, are generated with the aid of an output block which includes power semiconductor components which represent preselectably clocked output stages.
Publication DE 102 31 088 A1 furthermore refers to a switching device for the start system of a combustion engine of a motor vehicle. The switching device is suitable for switching on a starter motor which starts the starter motor upon request from a control unit. The switching device includes a transistor which is connected to a control unit as well as an arrangement for checking the functionality of the transistor.
Publication DE 10 2008 043 563 A1 discusses a starter control unit in which a redundant safety switch is implemented for turning off the start-stop function in the starter control unit.